Pneumatic hammer.



. Patented sept. 25, |900. E. A. Foam/cz.

PNEUMATIC HAMMER.

(Application led June 3, 1898.)

No. l658,542.

(No Model.)

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c rra PN EU MATIC HAM M ER.

srnoiFIcATIoN forming part of Lettere Pat-ent No. 658,542, datedseptember 25, 1900.

Application led June 3, 1898. Serial No. 682,424. (No model.)

To all whom, it may concern:

Be it known that I, EDMOND A. FORDYCE, of Chicago, in the county of Oookand State of Illinois, have invented certain new and useful Improvementsin Pneumatic Hammers, of which the following is a specification.

This invention relates to pneumatic hammers, and more particularly tothat classof portable hammers which are known as valveless, in which thestriking piston or hammer proper constitutes in itself thecontrollingvalve, by means of which its motion is reversed. l

My present invention has for its object to provide a hammerwhich shallbe simple and efficient and atthe saine time inexpensive in cost ofconstruction and maintenance, not liable to get out of order throughcomplication of parts, and in which the shock or vibration shall bereduced to a minimum.

To these ends my invention consists in certain novel features, which Iwill now proceed to describe and will then particularly point out in theappended claims.

In the accompanying drawings, Figure 1 is an elevation of a pneumatichammer embodying my invention. Fig. 2 is a central longitudinalsectional View of the same. Fig. 3 is a detail plan view of the upperend of the cylinder, the cylinder-head and piston or hammer-beingremoved. Fig. 4 is a detail plan view of the cylinder-head detached; andFig.'

5 is a detail sectional view taken on the same plane as Fig.'2, butshowing the piston or hammer in its uppermost position.

In the said drawings, 10 indicates the cyl inder or casing. Thiscylinder is provided with an internal chamber or bore 11 in its upperpart and a similar chamber or bore l2 in its lower part of less diameterthan the` chamber 11, there being thus formed between the two chambers ashoulder 13, which is annular in form. The chamber 12 is open at itslower end to receive the shank of the toolA from' the chamber 19 to thechamber 12 and openinginto this latter a short distance below theshoulder 13. The upper end of the port or passage 20 may be convenientlyformed by cutting a portion of the upper part of the cylinder-head 14,as indicated at 21 in Fig. 4, and communication is established betweensaid port 2O and the chamber 19 ,by means of suitable notches oropenings 22, formed in the lower edge of the handle 16, said notchesbeing formed at all parts ot the periphery of said handles, so that someone or more of saidv notches will register with the upper end of theport 20 when the handle is screwed home into proper position to clampthe head 14 in place.

23 indicates the piston or hammer proper, which is provided with anenlarged head or upper portion 24, which tits within the chamber 11, andwith a reduced lower portion 25,

which 'tits Within the chamber l2, there being:

thus formed upon -the body of said piston a shoulder 26- annularin'formand corresponding with the shoulder 13, against which it is adapted toabut. A short dist-ance below the shoulder 26 there is formed in Athebody of the reduced portionv 25 of the piston a circumferential groove27, which forms a port or passage for the compressed air at certainperiods of the operation of the device. Some distance below thiscircumferential groove or port 27 there is formed in the body of thepiston a second circumferential groove or port 28, which, by means ofpassages or apertures 29, is in communication with an opening or chamber30, formed in the interior of the piston 23 and extending from the portor groove 28 to theupper end of the piston, where it is in opencommunication with the chamber 11.

It will be observed that the chamber 30 is tapering in form so as toconform to the avail- IOO able space within the body of the piston andgive a relatively-large cubical capacity to said chamber, therebyincreasing the volume of coniined air which forms the air-cushion.

I have found by experience that this provision has a material effectupon the cushioning action and greatly increases the smoothness ofaction of the hammer.

31 indicates a. port or passage formed through the wall of the cylinder10 and communicating at its inner end with the chamber 11 at a point adistance above the shoulder 26 of the piston 23 about equal to thedistance between the ports 2O and 28 when the parts are in the positionshown in Fig. 2 of the drawings. The outer end of the port 31 opens intoor communicates with the atmosphere.

The admission of compressed air to the instrument is controlled by asuitable valve, the form which I have devised being that shown in thedrawings, the same being mounted in the handle 16 and comprising acylindrical valve 32, mounted'to move transversely with respect to theinlet-passage 18 in a suitable chamber or way 33 and adapted `to beprojected across the inlet-passage 18 so as to close or partially closethe same, as desired. This movement of the valve 32 is eected by meansof a lever 34, pivoted in a slot 35, formed in the handle, one end ofsaid lever engaging the valve, 32 so as to move the same, while theother end of the said lever rests upon a spring 36, by means of whichthe valve 32 is normally held in a closed position. The valve 32 isprovided with a stem 37, which engages with a suitable way 38 to guidethe movement of said valve.

The device thus constructed operates in the following manner: When theparts arein the position shown in Fig. 2 of the drawings, pressure uponthe lever 34 will open the valve 32 and air under pressure will beadmitted through the passage 18 into the chamber 19 and thence to theport or passage 20. From this latter the air under pressure passes intothe groove or port 27, and since the piston has been moved a sufficientdistance upward by its contact with the shank of the tool 39 to causethe upper end of the groove 27 to clear or pass upward beyond theshoulder 13 the'air under pressure is admitted into the space betweenthe shoulder 13 of the casing and the shoulder 26 of the piston. Thepiston is thereby caused to move upward, the air above said pistonescaping through the port 3l during such upward movement until theenlarged head or upper portion 24 of the piston closes said port 31.This occurs before the piston has reached the upper end of the cylinder,and the remaining air in said cylinder forms a cushion to prevent thepiston from striking the head of the cylinder and also to graduallyarrest the upward movement of the piston and minimize the jar or shock.At this time the parts have assumed the position shown in Fig. 5 and thegroove 28 comes opposite the port 20, the air thus passing through saidgroove and through the passages 29 and 30 to the space between thepiston-head and the upper end of the cylinder. The piston is therebycaused to move downward and deliver its blow upon the tool. The downwardmovement of the piston again uncovers the port 3&1, placing the same incommunication with the upper port of the cylinder 10, and the airisthereby exhausted therefrom and the downward movement of the pist tonis'arrested. During the latter portion of the downward movement of thepiston the air is compressed between the shoulder26 of the piston andthe shoulder 13 of the cylinder, thereby cushioning the closing portionof the downward blow of the piston. The rate of speed of the piston isvery great, reaching as high astwo thousand strokes per minute. As soonas the tool is withdrawn from the open lower end of the cylinder thepiston seats itself with its shoulder 26 in Contact with the `shoulder13 of the cylinder, at the same time cutting off communication betweenthe port 120 and the enlarged chamber or bore 11in the upper end of thecylinder, so that the relciprocation of the piston automatically stops`as soon as the shank of the tool is removed and is again started by theinsertion thereof, which raises the piston until the groove or port 27restablishes communication between the port 2O and the upper chamber orbore `11 of the cylinder.

The pneumatic hammer thus constructed gis, as is well known, capable ofa widely-exi tended range of applications, both as a metallworkersdevice and as a stone-workers delvice for chipping, calking,riveting,and all other purposes to which a continuously-operating hammeris adapted.

The machine constructed as described is `exceedingly simple and durable,being composed of but very few parts and not liable to -get out oforder, while at the same time it is easy to examine and repair, ifnecessary. The piston is cushioned at each end of its stroke and theshock, jar, or vibration is thereby reduced to a minimum.

Although I have described the device as a pneumatic hammer, it isobvious that fluidpressure of any suitable description may beM employedto actuate the hammer.

I claim- 1. A valveless pneumatic hammer comprising a cylinder having-abore of large diameter at its upper end and of small diameter at itslower end, each section of said bore being of equal diameter throughout,and a piston having an enlarged head and reduced body to fit said bore,the cylinder having an inlet-port opening into the reduced portionslightly below its top and an outlet-port opening from the enlargedportion above the normal downward position of the piston, and the pistonhaving an external groove or port slightly below its shoulder, a secondexternal groove or port below said first-mentioned groove or port,

IOO

IIO

and a passage extending from the upper end of the piston to said lowergroove or port, the lower end of the cylinder being closed by the pistonthroughoutits range of movement, substantially as described.

2. A pneumatic hammer, comprising a cylinder or casing having a bore orchamber of unequal diameter in its upper and lower portions, an air portor passage opening into the reduced lower portion a short distance belowthe shoulder between the two portions, and an exhaust-port opening intothe larger upper portion above said shoulder, and a piston or hammerproper having an enlarged head to iit the upper portion of the cylinder,a smaller body to it and close the lower portion of the cylinder, anexternal groove a short distance below the shoulder thus formed, apassage or piston below the iirst-mentioned groove and communicatingwith the internal passage or chamber thereof, substantially as'described.

3. In a pneumatic hammer' of the class described, the combination, witha cylinder and its piston,said cylinder being open and threaded at itsupper end and provided with a seat below said threaded portion, of acylinder'-y head shouldered to t saidseat, and a handle threaded to fitthe cylinder above the head thereof and hold the latter in position,said handle being recessed at its lower end to form an air-chamber andnotched at its extremity to form air-passages between it and thecylinder-head,whereby said air-chamber com muni= cates with the interiorof the cylinder, sub' stantially as described.

EDMOND A. FoRDYcE'. y

Witnesses I FREDERICK C. GOODWIN, IRVINE MILLER.`

